How Does Light Influence the Rate of Capture in a Video Camera 🌱

Here’s a video I saw on reddit of someone flicking a ruler to make it vibrate in low light vs a much lighter area. https://i.imgur.com/l0LqeWl.gifv

Even though the ruler looks like it’s moving faster in the low light, the camera is actually capturing information more quickly when the ruler vibrates in the area with more light.

• The wavelike vibration of the ruler is likely a result of the camera capturing information a rate such that the frequency of frames being captured is a multiple/divisor of the frequency of the vibration.

A camera shutter is a device that lets light through for a brief duration. If the aperture controls the area through which light can pass, the shutter controls the time period over which light can pass. This means, the longer the shutter stays open, the more light passes through.

• Rolling shutter is where a image is captured by scanning across a scene rapidly, so that you capture different parts of the scene at different times.
• Global shutter is where the entire frame is captured at the same instant.

When you take an image in an area with only a small amount of light, the camera has to expose the frame for longer to be able to capture the whole image, so each image in a video will be a little blurry because objects will have moved while the shutter is open. When there’s more light, the camera has to expose the frame for a shorter amount of time so you can still see the detail in objects with motion.

In cameras in the UK for a video, images are taken 25 times per second (so videos are 25 fps or frames per second), which is constant. So in the 1/25th of a second, the camera takes 1 photo but it can vary between a super quick photo (if there’s a lot of light) or using the entire 1/25th of a second to let through as much light as possible.